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Full text of "Practical Organic Chemistry"

PRACTICAL ORGANIC CHEMISTRY

distils, and when the temperature passes 180° the distillate sol-
idifies, and consists mainly of acetamide'. The yield is, however,
small. A better result is obtained by first heating the ammonium

FIG. 55.

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acetate in sealed tubes. The ammonium acetate, if not procur-
able, may be prepared by adding to 70 grins, glacial acetic acid,
warmed in a basin on the water-bath, about 80 grins, powdered
ammonium carbonate until the acid is neutralised, which is re-
cognised by diluting a sample with a little water, and testing
with litmus.

Heating under Pressure.—Two tubes are made from the
usual thick-walled tubing by sealing one end (see p. 24). These
are gently warmed, and the melted acetate poured in until they
are about half full. They are then sealed in the manner described
on p. 24. The tubes are then placed in a tube furnace (p. 23)
and gradually heated to 200°, at which temperature they are
maintained for 5—6 hours. Without removing the tubes from the
furnace they are allowed to cool, and the capillary end opened by
holding a Bunsen burner to the tip until fused, when the pressure
within perforates the glass. If a deep file scratch is then made
about an inch below the sealed end and the end of a red-hot glass
rod held against the scratch, a deep crack is produced and the end
easily removed. After heating, the tubes contain a clear,, oily-
looking liquid, which consists of an aqueous solution of acetamide,
together with some unchanged acetate. The contents are poured
into a distilling flask and distilled with a straight tube as
condenser, and the portion boiling above 180° collected in a

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